Visual Perception and Analysis of an Approaching Train at Railway Level Crossings in New Zealand

Abstract

The prevalence of railway level crossing accidents in New Zealand is a high profile issue that has warranted close scrutiny over the last 10 years. However, the incident rate has not decreased. This research examined the possibility that visual illusions and perceptual errors contribute to an underestimation of a train‟s arrival time by motorists. The first experiment was designed to analyze whether the Size-Arrival Effect, a theory that states that large-far objects are judged to arrive earlier than small-nearer objects, was applicable to trains. Participants were shown a computer simulation of a moving vehicle (train, motorcar or motorcycle) and asked to indicate when the point was reached where they would no longer cross in front of the approaching vehicle. Approach speeds were systematically varied (60 km/h, 70 km/h, 80 km/h, 100 km/h and 120km/h). Results found that participants adopted the greatest safety gap distance to cross for the train. However, there was no adjustment for velocity when adopting safety gaps for the train and the motorcycle with observers using the same gap distance, regardless of the approach speed. The second experiment sought to examine the Leibowitz hypothesis (Leibowitz, 1985), which proposes an illusory bias; a large object seems to be moving more slowly than a small object travelling at the same speed. Experiment 2 measured participants' ability to make a direct comparison between the speed of an approaching motorcar and a train. Participants were asked to judge which of the vehicles appeared faster, with the distance from the observer varied (far, middle or near). Participants significantly underestimated the speed of the train as compared to the car, in both the 'middle' and 'near' conditions, with the magnitude of underestimation greatest in the 'middle' condition. The overall findings offered support for both theories, which indicates that a combination of distance and speed perceptual errors may at least partly contribute to the high rates of level crossing collisions.